Systems, devices, and methods for control of a power supply connection

Abstract

A power supply control circuit for a portable electronic device is capable of connecting and disconnecting a power supply with respect to an electrical load of the device. The power supply control circuit offers a relatively quick transition time and low leakage current, making the control circuit particularly suitable for applications that require the power supply to remain connected to the electrical load at all times.

What is claimed is: 
     
       1. A method of disconnecting a power supply from an electrical load in a portable device having a first transistor electrically located between the power supply and the electrical load, a second transistor having a gate coupled to an input node, a third transistor having a gate coupled to the input node, and a fourth transistor, the method comprising:
 deactivating the third transistor with a first voltage applied at the input node; 
 activating the second transistor with the first voltage applied at the input node; 
 deactivating the first transistor with a second voltage applied by the second transistor, wherein deactivation of the first transistor electrically disconnects the power supply from the electrical load; and 
 activating the fourth transistor with the second voltage to maintain the deactivation of the third transistor. 
 
     
     
       2. The method of  claim 1 , wherein a resistive feedback path is present between the electrical load and the input node, and a first capacitor is coupled between the input node and a ground node, the method further comprising applying an impedance to the input node such that the input node effectively resembles an open circuit. 
     
     
       3. The method of  claim 1 , wherein every path between a positive terminal of the power supply and a ground node passes through a transistor or a capacitor. 
     
     
       4. The method of  claim 1 , wherein no path exhibiting only a resistance exists between a positive terminal of the power supply and a ground node. 
     
     
       5. The method of  claim 1 , wherein the first voltage applied at the input node is applied by an output line of a processor. 
     
     
       6. A method of operating a portable reader device comprising a control unit, a power supply, and a power supply control circuit coupled with the power supply, the method comprising:
 applying, by the control unit, a control signal to an input node of the power supply control circuit to connect the power supply to an electrical load of the portable reader device; 
 connecting, by the power supply control circuit, the power supply to the electrical load; and 
 performing, by the control unit, a power down routine that powers off the portable reader device such that the portable reader device enters a powered off state with the power supply remaining connected to the electrical load, wherein no electrical path exists between the power supply and a ground node other than through a transistor or a capacitor. 
 
     
     
       7. The method of  claim 6 , wherein the control unit applies the control signal to the input node after sensing a command to power on the portable reader device. 
     
     
       8. The method of  claim 7 , wherein the control unit performs the power down routing in response to sensing a command to power off the portable reader device. 
     
     
       9. The method of  claim 6 , further comprising sending a request to an on-body electronics device for data indicative of a sensed analyte level of a subject. 
     
     
       10. The method of  claim 9 , wherein the request is sent using a near field communication (NFC) protocol. 
     
     
       11. The method of  claim 6 , further comprising receiving data indicative of a sensed analyte level of a subject using a Bluetooth protocol. 
     
     
       12. The method of  claim 6 , wherein the portable reader device is a smartphone.